The invention relates to a slide ring seal, and in particular a running gear seal accordance with the category-defining part of the first patent claim.
In the case of running gear seals with rubber rings, penetrating contamination under high pressure (for example a turning maneuver on a bulldozer) exerts an axially acting force on the rubber rings. A force that opposes the requisite closing force can not only reduce the axial force creating the closing force, but even cancel it completely, so that contamination is able to penetrate through the sealing gap of the slide ring seal, for example into a downstream transmission. With increased friction, increased force can result in overheating and, consequently, in damage to the seal.
This problem has long been known, and transmission wear-out and transmission failures as a result of seal failure are unacceptable.
A first attempt at a solution is described in DE 199 55 860 A1. The slide ring seal disclosed here, which in particular is a running gear seal, comprises an angular slide ring and/or counter ring with a specific circumferential surface for receiving an annular sealing element with an approximately plate-shaped cross section, the sealing element containing a secondary seal in the region of the sealing shank. In this attempt at a solution, it has been shown that if contamination penetrates from outside, the secondary sealing lip will fold in, and thus the problem is the same as described above.
U.S. Pat. No. 4,256,315 relates to a slide ring seal, and in particular a running gear seal which, analogously to DE 199 55 860 A1, is likewise provided with a secondary seal. That seal is either located, in parts, on the outer circumferential surface of the glide ring or the counter ring respectively, or on the full surface thereof. Here again it is inevitable that the axial forces created as a result of the penetration of dirt cause the slide ring seal to open, entailing disadvantageous penetration by dirt.